Oral Anatomy Ch. 3

teeth posses certain characteristics of

shape and alignment (their position in the jaw)

proximal contact areas

where the proximal surfaces of teeth touch one another

a proximal contact prevents

food from packing between teeth

a proximal contact protects

the underlying gum tissue

a proximal contact offers

support and anchorage to teeth

two adjacent teeth share

the same interproximal bone

the bone that supports the ______ root portion of the first tooth also supports the ______ root portion of the second tooth

distal, mesial

the proximal contact areas are located on the medial and distal surfaces of each tooth at the

widest portion and the greatest curvature

the distal contact area of one tooth touches the ______________ of the tooth posterior to it

medial contact area

the ____________ is a flattened portion of the tooth where it touches the tooth next to it in the same dental arch

contact area

a ____________ is where the occlusal cusp of one tooth touches the occlusal portion of another tooth in the opposing arch

contact point

the proximal contacts do not take up the entire surface, but a considerable portion of the proximal surface does touch the

adjacent tooth

interproximal spaces are

triangular-shaped spaces between the teeth formed by the bone on one side and the proximal surfaces and their contact area on the other side

the contact area of interproximal spaces forms the

apex of the triangle

the proximal surfaces of interproximal spaces forms the

sides

the alveolar bone of interproximal spaces makes up the

base

the interproximal spaces are normally filled with gingival tissue called

papillary gingiva or interdental papilla

interproximal spaces are wider cervically than occlusally to provide

more access for the vascular support to nourish the interdental bone and papillary tissue

when gingival recession occurs between the teeth

the interdental papilla and bone no longer fill the entire interproximal space

avoid that exists cervically to the contact area is known as a

cervical embrasure

the more bone that is missing

the larger the interproximal space

embrasures (spillways)

are the spaces between the teeth that are occlusal to the contact areas

embrasures allow for the passage of _______ around the teeth so that it is not forced into the contact area between the teeth

food

embrasures are named for their location in relation to the contact area

facial (buccal or labial)

lingual

incisal

occlusal

if the interproximal space is not occupied by any gingiva or bone the

gingival embrasures are evident

the gingival embrasure is gingival to the contact area and

not usually present

embrasures allow food

to be moved away from contact areas

embrasures dissipate and reduce

the forces of occlusal trauma

embrasures provide self-cleaning by the action of

the tongue, cheeks, and lips

embrasures protect the gingiva from

undue trauma

contact areas of the anterior teeth are located

closer to the incisal surfaces of the teeth

contact areas of posterior teeth are nearer the

middle third of the teeth

the more posterior the tooth, the more cervical the

location of its contact area

one exception its the distal contact area of the

maxillary canine, its location is in the center of the middle third of the tooth

the more posterior teeth also have wider embrasures than

anterior teeth

the interproximal spaces of posterior teeth become

shorter occlusocervically

the location of the contact areas and embrasures, as seen from the occlusal surface, shows the contact areas of the anterior teeth are located in

the center between the labial and lingual surfaces of the tooth

the posterior teeth have contact areas slightly

buccal to the center of the teeth

buccolingually the lingual embrasures are wider than the

facial embrasures

teeth are narrower on the

lingual side than on the facial side

facial and lingual contours of the teeth

direct food off the teeth

the correct degree of facial or lingual curvature allows for the

proper deflection of food

the contour on the lingual surface allows the tongue to rest against the tooth to promote the

most efficient self-cleaning

the facial height of contour allows for maximum

cleaning of the lips and cheeks

in general the location of the buccal height of contour of anterior and posterior teeth is at the

cervical third of the tooth

the height of contour is the same as the crest of curvature and refers to

the buccal or lingual width of a tooth

the lingual height of contour of anterior teeth is at the

cervical third of the tooth

the lingual crest of curvature of posterior teeth is at or near the the

middle third

the normal amount of curvature found on most facial contours is approximately

0.5mm and is somewhat less lingual on the anterior teeth

the amount of curvature on the lingual side of maxillary posterior teeth averages approximately

0.5mm and on the mandibular posterior teeth, it averages approximately 1mm

the crowns of anterior teeth have a greater curvature of the cervical line, or CEJ, medially and distally than do the

posterior teeth

this curvature affords more anchorage and

bony support

the enamel on anterior teeth does not go as far gingival on the

medial and distal surfaces

due to the enamel not going far gingivally the bone has more cementum to

attach to

the periodontal attachment follows the cervical line and connects the

gingiva and the cementum

the periodontal ligament attaches the cementum to the

bone

the maxillary anterior teeth show the greatest amount of curvature of the

cervical line

the more anterior the tooth the

greater the curvature

the medial curvature of a tooth is greater than the

distal curvature of the same tooth

the mandibular anterior teeth show less curvature than their

maxillary counterparts

the posterior teeth in both arches show little

variation

as a general rule, the curvature of the CEJ is usually about

1mm less on the distal surface of the tooth than on the medial surface

if a maxillary incisor has a 3.5mm medial curvature of the CEJ, the distal curvature may be

2.5mm

to a large extent the teeth are self-cleaning in that the crowns of the teeth are covered by

very smooth enamel

the smoothness of enamel helps food and sticky substances slip off the crown of the tooth and allows the tooth to remain relatively free of

bacteria, thus lessening decay and periodontal disease

the shapes of the teeth reflect their functions and

self-cleaning ability

the canine is a piercing

tool

the premolars are shaped in such a way that food is deflected onto the occlusal surface of the premolar, where

it is ground up by the cusps of the teeth in the opposing arch

when food is introduced into the mouth, it is aided by the tongue and cheek in pushing the previously pulverized food

back onto the surface of the molars

self-cleaning process continues from molar to molar until the food

reaches the back of the mouth and is swallowed

if deep pits and fissures on the occlusal surface of the tooth are evident, some of the food debris

remains after eating

pits and fissures provide a method of dissipating the extreme occlusal forces that result from the

interdigitation of the cusps in the process of grinding up food

pits and fissures act as spillways on the

occlusal surfaces of the teeth

modern dentistry has found ways to reduce the

pits and fissures of teeth

a pit can be polished out, making a tiny unclean able hole into a small, more

cleanable fossa

the process of polishing out a pit is called an

odontectomy or odontoplasty

a pit can be filled in and covered with a

sealant or bonding procedure

the periodontium is the supporting tissue adjacent to the

teeth

periodontium consists of the

free gingiva

attached gingiva

alveolar mucosa and the cementum

periodontal ligament

bone

the tissues of the periodontium are essential for the

support and anchorage of the teeth

the buccal and lingual contours of a tooth are shaped so that food is

deflected off the tooth

the angle at which the food is deflected is

specific

if the curvature is too extreme, the food is deflected in such a way the the gingival tissue is

not cleaned by the frictional action of the food that deflects off of it

when the bacteria cannot be removed from the free gingival collar around the tooth

it could begin to destroy the gingival tissue

the contact areas are equally essential to the health and maintenance of the

periodontal tissue in the interproximal spaces

if open contacts are present the teeth do not touch each other at their contact areas, and food is allowed to pack

between the teeth and remain there

the bacteria captured on and in the gingival crevice could cause a

periodontal breakdown of these tissues

if the contact area is wide open, as in a diastema, food can be forced into the interproximal space but does not

remain because of the extremely large size of the space

if the deflection of the food is at an extreme angle

a recession of the tissues away from the crown of the teeth could result

when gingival tissue recess from the tooth

the root of the tooth becomes exposed

when a tooth is restored by some type of dental material, it is important that the margins of the restorations be

smooth and approximately the normal shape of the tooth as much as possible

if the margins are rough, they will allow bacteria to be retained around the

restoration and thus cause gingival inflammation and decay

if the margin of a restoration extends far beyond the tooth, known as overhanging restoration, it allows the buildup of

plaque, bacteria, and food

canines and posterior teeth have from 1-5

cusps

most cusps are names after the closest tooth surface or

line angle

two triangular ridges may join to form

one transverse (or oblique) ridge

mamelons

form on adult incisors from three labial lobes; usually wear away

perikymata

very small wave-like ripples of enamel on newly erupted adult teeth

buccal cervial ridge

near CEJ mesially

fossae

shallow bowl-like depressions often with grooves or pits